the Poor Man 660 support thread

[analag]

Very, very nice indeed.

analag

 

[rrs]

My Stereo PM660 is now up and running  ;D

BUT!!

I have a slight issue with the gain and threshold controls. One channel seems to influance the other and gain setting seem differect for each as does the threshold.

I have wired PSU to channel 2 then to channel 1.
Should I wire both channels directly to PSU?

Or is the problem likly to be somewhere else? have checked rotary switches and all seems fine same with wiring.

 

[lolo-m]

My Stereo PM660 is now up and running  ;D
BUT!!

Good to know it's working !
I like star-grounding and I like to star supply wiring from PSU boards...
I don't know if it'll solve your problem but I think it's a better way to do...

Maybe the weird looking 6BC8 is where your problem is... Try to change the tubes from one board to the other to see if the problem changes too (it'll be the tubes), then if it stays on the same side, try to exchange the gain pots, test... Repeat with threshold pot, then transformers... If there's an easy way to find, you'll find by possibilities elimination...

 

[veermaster]

My first channel is set up in "experimentation mode": I want to try different sidechain mods suggested here and other things but I got one question about RV3 and RV6:
I know these should be trimmed to get -2,4V and -4,5V, but when playing around with these I noticed that I get really nice distortion when  raising RV3. I will include this as an effect with a switch but was wondering if there are any reasons I should not so (safety etc).
The reason I ask is because I don´t have the technical knowledge to understand the function of RV3 and RV6.
Thanks, emre

 

[skal1]

Are the stereo boards hook up serial or parallel ?

regards

skal1

 

[lolo-m]

My first channel is set up in "experimentation mode": I want to try different sidechain mods suggested here and other things but I got one question about RV3 and RV6:
I know these should be trimmed to get -2,4V and -4,5V, but when playing around with these I noticed that I get really nice distortion when  raising RV3. I will include this as an effect with a switch but was wondering if there are any reasons I should not so (safety etc).
The reason I ask is because I don´t have the technical knowledge to understand the function of RV3 and RV6.
Thanks, emre

RV6 sets upper grids polarisation, this polarisation will be more negative when compressing.
RV3 sets the anode polarisation.
Both sets the non-compressing operation point of the 6BC8.
To know if you're going to damage your tubes, you've got to measure the voltage and current at the anode of the 6BC8. If it the multiplication give less power than what they can accept, it is safe, if not you will damage your tubes.

 

[veermaster]

RV6 sets upper grids polarisation, this polarisation will be more negative when compressing.
RV3 sets the anode polarisation.
Both sets the non-compressing operation point of the 6BC8.
To know if you're going to damage your tubes, you've got to measure the voltage and current at the anode of the 6BC8. If it the multiplication give less power than what they can accept, it is safe, if not you will damage your tubes.

Ah, thanks for your reply lolo! Do I have to measure when compressing or non compressing or does it not matter?

 

[lolo-m]

RV6 sets upper grids polarisation, this polarisation will be more negative when compressing.
RV3 sets the anode polarisation.
Both sets the non-compressing operation point of the 6BC8.
To know if you're going to damage your tubes, you've got to measure the voltage and current at the anode of the 6BC8. If it the multiplication give less power than what they can accept, it is safe, if not you will damage your tubes.

Ah, thanks for your reply lolo! Do I have to measure when compressing or non compressing or does it not matter?

Both !!!
When compressing, current is little, but voltage big.
Without compression, current is high and voltage low.
Measure both situation, allow about 5 or 10% of margin power for security ( curves maybe vary during compression ).

 

[gevermil]

Has anyone here used these ebay switches ?
http://cgi.ebay.com/1-PC-Selector-Switch-24-step-2-pole-Attenuator-Pot-New_W0QQitemZ280313607493QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280313607493&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

If they have been mentioned in this thread Im sorry .

Just looking for the good buy
thanks
gary

 

[veermaster]

Thanks again lolo!
emre

 

[Holger]

Has anyone here used these ebay switches ?
http://cgi.ebay.com/1-PC-Selector-Switch-24-step-2-pole-Attenuator-Pot-New_W0QQitemZ280313607493QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280313607493&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

If they have been mentioned in this thread Im sorry .

Just looking for the good buy
thanks
gary

I have purchased four of them. They are cheap in any regard.
1. the adjustment range is 345° rather than then usual 270°-300°.
2. some holes are too small for 2 resistor legs.
It will take hours to solder one switch. I didn't had the money to buy Goldpoint switches, I wish I had...

 

[lolo-m]

Has anyone here used these ebay switches ?
http://cgi.ebay.com/1-PC-Selector-Switch-24-step-2-pole-Attenuator-Pot-New_W0QQitemZ280313607493QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280313607493&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

If they have been mentioned in this thread Im sorry .

Just looking for the good buy
thanks
gary

I use those too. They're perfect for the job... If I do remember well, bernbrue uses them too.
Warning : overall diameter with resistors is about 34mm. (it can be a problem in some cases)
If someone has got a tip to reduce those switches from 24 positions to 20 I am interrested ! I must admit I didn't try to open their back so...

 

[mich]

If someone has got a tip to reduce those switches from 24 positions to 20 I am interrested ! I must admit I didn't try to open their back so...

Its possible to reduce the # of positions by opening the switch (carfully..) and inserting a piece of those small plastic retainers that you would use to hold your wires together...
there is a curved slit inside - thats where you put the small piece of plastic. - once you open the switch it will all be clear.....

 

[bernbrue]

Has anyone here used these ebay switches ?
http://cgi.ebay.com/1-PC-Selector-Switch-24-step-2-pole-Attenuator-Pot-New_W0QQitemZ280313607493QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280313607493&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

If they have been mentioned in this thread Im sorry .

Just looking for the good buy
thanks
gary

Hi,
these are the Uraltone switches. I used them for my PM670 prototype. They are not as good as the Elma ones but good quality for a reasonable price.
regards
Bernd

 

[SIXTYNINER]

GREAT JOB
klaus2you

nice 660 on the "club"

6T9R

 

[veermaster]

Just to be on the safe side:
refering to the shematic on which leg of RV3 and RV6 do I measure the to be adjusted voltage?
One more question:
I played around witch different meters and values for R6 + additional paralleled trimmers: whatever I do the needle of the meter is constantly moving back and forth and indeed: when measuring voltage across R6 it is raising and dropping constantly! Does anybody have an idea what´s wrong?
Thanks a lot, Emre

 

[veermaster]

Don´t mean to be impatient, but is there anyone who could help me out?
Thanks, Emre

 

[bernbrue]

Hi Emre,
just a few ideas: check PSU for constant 136V, +/-17V. Check also the wiring of T2. Check the transformer itself. What about Q1, isolated from ground? I had problems with a bad solder contact at the trimmers (RV3, RV6). What kind of meters do you use? Do the meters of both channel react the same way? Hope it helps a bit.
regards
Bernd

 

[Grooveteer]

Just to be on the safe side:
refering to the shematic on which leg of RV3 and RV6 do I measure the to be adjusted voltage?

Hi Emre, you measure between pin 2 of trimmer and ground.  (Not that I knew this but Volker said so on page 20 of this thread  )

Cheers,
G

 

[veermaster]

Thanks Grooveteer, must have overlooked that.
And thanks Bernd for your help.
At the moment I have only built one channel, so no comparison possible 
I checked voltages from PSU, they are stable. ALso switched T2, still the same, and yes, Q1 is isolated.
At the moment I use a DC meter because my SIfam AL22 seems to have a too high internal resistance. I took out the rectifying part out of another AL22 before and got it working with the PM660 but I accidently dropped it, and well, we might meet again in heaven. :-\
BUT:
I tried disconnecting the other Transformers as well. When I disconnect Nr4 the needle stops moving back and forth so I guess it must be something in the sidechain section.
Anybody knows what to check?
Thanks in advance, Emre